agent/src/main/java/com/code_intelligence/jazzer/utils/ManifestUtils.kt

// Copyright 2021 Code Intelligence GmbH
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.code_intelligence.jazzer.utils

import java.util.jar.Manifest

object ManifestUtils {

    private const val FUZZ_TARGET_CLASS = "Jazzer-Fuzz-Target-Class"
    const val HOOK_CLASSES = "Jazzer-Hook-Classes"

    fun combineManifestValues(attribute: String): List<String> {
        val manifests = ClassLoader.getSystemResources("META-INF/MANIFEST.MF")
        return manifests.asSequence().mapNotNull { url ->
            url.openStream().use { inputStream ->
                val manifest = Manifest(inputStream)
                manifest.mainAttributes.getValue(attribute)
            }
        }.toList()
    }

    /**
     * Returns the value of the `Fuzz-Target-Class` manifest attribute if there is a unique one among all manifest
     * files in the classpath.
     */
    @JvmStatic
    fun detectFuzzTargetClass(): String? {
        val fuzzTargets = combineManifestValues(FUZZ_TARGET_CLASS)
        return when (fuzzTargets.size) {
            0 -> null
            1 -> fuzzTargets.first()
            else -> {
                println(
                    """
                    |WARN: More than one Jazzer-Fuzz-Target-Class manifest entry detected on the
                    |classpath.""".trimMargin()
                )
                null
            }
        }
    }
}